There are a number of prior art patents related to synthesis of aluminum phosphate materials primarily for use as a catalyst support including crystalline and amorphous forms. Most synthetic methods comprise of using a sol-gel technique with raw materials that include commonly available salts of aluminum and a variety of phosphorous sources including phosphoric acid, ammonium hydrogen phosphates, phosphorous acid, and others. Many of these methods yield crystalline forms and few thermally stable amorphous compositions (U.S. Pat. No. 4,289,863, Hill and al.; U.S. Pat. No. 5,698,758, Rieser and al.; U.S. Pat. No. 6,022,513, Pecaro and al.). The prior art materials, for example, cannot be used as a coating for protecting substrates from corrosion or oxidation at elevated temperatures.
It is desirable to use an amorphous dense coating that is thermally durable and stable to protect various substrates in industrial and consumer use applications. The prior art coatings are either not durable under certain atmospheric conditions or under certain harsh industrial or use environments where materials are subjected to thermal treatments or exposed to corrosive environments. Silica-based amorphous coatings have been developed and a recent patent prescribes a unique way to deposit such coatings (U.S. Pat. No. 6,162,498). However, the coating is not durable under certain harsh conditions and is not thermally stable at elevated temperatures or do not serve adequately as a transparent coating on glass. High temperature stable glassy or vitreous coatings have also been developed by initially coating substrates with a slurry of glass frits and subsequently treating the coated material to high enough temperatures to melt the glass fits and form the vitreous coating. Vitreous enamel coatings have been in existence for many decades with many different compositions. However, they are usually thick and deform at elevated temperatures. The requirement of high temperature processing to melt the glass frits may degrade the substrate and if low melting glass compositions are selected, they may not be durable.
Vapor deposited inorganic coatings are currently under use for many applications, however, they require expensive equipment and are not suitable for non-line of sight substrate geometries (For example, U.S. Pat. No. 3,442,686, U.S. Pat. No. 4,702,963, U.S. Pat. No. 5,434,008, U.S. Pat. No. 5,792,550). Solution-derived inorganic coatings provide low-cost and conformal ability to coat substrates.
Some of the prior art inorganic coatings are also not completely transparent for use on glass where transmission properties are affected or other substrates where aesthetic property of the substrate (metallic appearance) needs to be preserved.
Brushed steel and other related solid surfaces are used extensively in facades in buildings, malls, elevators, table lamps, bath fixtures, cabinet doors, wall plates and others. Desirable properties of these surfaces include easy-to-clean and finger print resistance along with adequate durability under exposure from thermal load or heat, sun-light, various solvents and common cleaning agents, UV-radiation, and provide non-stick against foods and other related properties.
Porous surfaces are susceptible to contamination when used for storage and like purposes. Enamel, granite, marble, floor tiles, glass, porcelanized stoneware, oven and related cooking appliances in a kitchen, oven interior panels, food trays, cooktops and other ceramic surfaces possess micro as well as macro pores and defects which are not desirable in their end application. Sealing of pores on granite, for example on kitchen countertops, will help impart anti-staining properties. Hermetic sealing of these pores will also help reduce gas permeation which is important in certain applications. Polymer surface treatments are well known in the art to seal ceramic surfaces, however, their durability is limited under heat, exposure to cleaning solvents or agents, and are relatively soft. A suitable thin inorganic coating which is chemically inert and thermally stable is desired. Many of these applications represent high volume sales such that low cost coating techniques are important for consideration with solution-based dip or spray coating being the most preferred method of application. Such treatments can also enable self-cleaning surfaces, easy-to-clean, biosafety, aesthetic value, hardness and abrasion resistance, antimicrobial combined with solvent resistance. Also, such a sealant should have good thermal shock properties (for example, hot pan on granite table) and thermal stability; even if the sealant is worn off, the effect of filling pores on the surface would help extend the durability of the coating significantly. Inventive material on anodized aluminum parts and other related materials can provide improvements to performance and durability along with environmental and energy savings. The inventive material can be used as a hermetic sealing of ceramics and adhesion promoter (monolithic, composites, and glass-ceramic) in various applications including tile, substrates for electronic packaging and refractories to improve durability and lower gas permeability.
Silicon carbide has excellent properties for space-based and airborne platform optical materials, but the brittle nature along with the high hardness of the material makes it difficult to finish to tolerances required. Polishing the surface to a fraction of the wavelength of light to be reflected takes weeks to months, depending on size and shape of the substrate.
Current low dielectric materials do not have the required dielectric constant values in combination with thermal and mechanical stability. New low k materials are required to improve the present state of semiconductor field.
Researchers are working to combine polymer and metal-foil substrates with printable TFT backplanes to move flexible displays closer to commercial reality. For years, the “holy grail” of the display industry—as of yet, largely unobtainable—has been a thin, clear, flexible substrate with barrier properties equal to those of a sheet of glass. Again, the prior art has been somewhat deficient in this regard.
Photomasks are high precision plates containing microimages of electronic circuits. Architecture should be maintained to achieve defect free photomasks. Problems arise when the chrome layer is affected by environments or interlayer reactions. There are cosmetic defects including scratches on the chrome outside the array, damaged or partially removed AR coating, contamination on the chrome, glass chips on the edge of the mask, etc.—all of which need to be avoided. Coatings should be very thin, in the range of approximately 10 nanometers, and defect free.
Plastic materials, in general, are susceptible to degradation from abrasion, moisture attack, UV radiation, atomic oxygen, exposure to solvents, chemicals and many others. Vapor deposited inorganic coatings on plastics are currently under use for many applications, however, they require expensive equipment and are not suitable for non-line of sight substrate geometries (For example, U.S. Pat. No. 3,442,686, U.S. Pat. No. 4,702,963, U.S. Pat. No. 5,434,008, U.S. Pat. No. 5,792,550). Therefore, there is a need for low-cost solution-derived protective coatings (inorganic and inorganic-organic composite) for plastic substrates with suitable processing schemes to develop reel-to-reel or roll-to-roll continuous processing as well as the ability to coat complex-shaped substrates.
Unlike glass and metal, however, all polymers exhibit a measurable degree of permeability to gases and vapors. Numerous technologies have been developed to decrease the permeability of polymers, and thus increase their range of applicability to food and beverage packaging. A permeation barrier layer is also important whenever a permeant material has to be transported. Tubes and hoses for gasoline, fluorocarbon vapors, etc. (important in automotive and appliance applications), require barrier performance beyond that currently available. Likewise, thin defect and pinhole-free inorganic moisture and oxygen barrier coatings are need for these display applications.